Well, some (far from all) mentally out-of-phase people are dangerous, and, being such, are equivalent to having on themselves a concealed weapon (they themselves being a weapon, in a sense).
Therefore, to stay within the law, they would need to apply for and to receive a [special] CCW permit. Such application cannot be carried out without identifying them first, for which purpose the testing is obviously necessary.
If, on another hand, due to their mental condition, the CCW cannot be issued, then, since they are walking equivalents to CCW anyway, and therefore are in violation, they are to be removed from the streets via mandatory institutionalization, for which purpose the testing is equally necessary.
I was talking about pregnanat women and children.